High capacity high data rate frequency hopping networks

Multiuser detection for frequency hop spread spectrum multiple access (FH/SSMA) systems has been traditionally done by conventional single user decoding or by erasure techniques. We study the demodulation and decoding aspects of multiuser reception for SFH/SSMA and propose methods which improve the capacity of the system. In particular, we propose and analyze the joint demodulation of multiple symbols and the use of iterative decoding after the demodulation. For the hard decision demodulation, need Solomon codes of different users collaborate with each other after the joint demodulation to reduce the multi-user interference. This approach is then extended for the soft decision demodulation and decoding where a block turbo code consisting of two shortened RS codes is employed. Results are shown both for synchronous and asynchronous frequency hop systems and indicate considerable improvement over the conventional systems.